A computer network is a collection of interconnected computing devices that exchange data and share resources. In a packet-based network the computing devices communicate data by dividing the data into small blocks called packets. Certain devices within the network, such as routers, maintain routing information that describes routes through the network. In this way, the packets may be individually routed across the network from a source device to a destination device. The destination device extracts the data from the packets and assembles the data into its original form. Dividing the data into packets enables the source device to resend only those individual packets that may be lost during transmission.
Virtual private local area network service (VPLS) domains are often used to extend two or more remote customer networks, i.e., VPLS sites, through a service provider (SP) network and possibly other intermediate networks, such as the Internet, as if the intermediate networks does not exist. VPLS domains provide point-to-multipoint (P2MP) connectivity, and may transport layer two (L2) communications, such as Ethernet packets, between customer networks via the SP network in a P2MP fashion. In a typical configuration, routers coupled to the customer networks define a full mesh of label switched paths (LSPs) within the SP network to carry encapsulated L2 communications as if these customer networks were directly attached to the same local area network (LAN).
In some cases, a VPLS domain may be configured to carry L2 multicast traffic, such as Internet Protocol Television (IPTV), desktop conferences, corporate broadcasts, music and video web casts, and other forms of multimedia content, to subscriber devices within the customer networks.